build_face_rig

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full behavioral burden and does not meet it. It implies a mutation (creating shape keys) and a dependency on a 'rig-approved exact' version, but says nothing about permissions, reversibility, side effects on existing keys, or execution cost.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence with no filler, so it is efficient. It is arguably too terse given the complexity, but on the conciseness dimension it wastes nothing.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return values need not be described. But for a mutation tool with five parameters, zero schema coverage, and no annotations, the description is far too thin to guide correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0% and all five parameters are undocumented in the schema. The description gestures at 'source version' and 'facial shape keys' (likely blendshape_set), but project_root, character_id, and request_id are left completely unexplained.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (Create) and resource (facial shape keys), which implicitly distinguishes it from the broader rig_character sibling. However, it does not name an alternative or clarify how it relates to rig_character, so the differentiation is inferred rather than stated.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no explicit when-to-use guidance or mention of alternatives such as rig_character. The phrase 'rig-approved exact source version' hints at a precondition, but it is never spelled out as a usage rule.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.